(1) Field of the Invention
This application is a 371 application of PCT/EP2008/011166 filed Dec. 20, 2008, which claims priority to the German application 20 2008 000 455.1 filed Jan. 11, 2008.
The invention relates to a damping device, in particular for damping the movement of movable furniture parts of pieces of furniture, with a piston which is mounted so as to be longitudinally displaceable in a housing and which as a function of its displaced position forms working chambers filled with a fluid damping medium on opposing sides of two working chambers of variable size filled with a fluid damping medium, which by way of at least one overflow connection enables a throttled overflow of the damping medium between the two working chambers, wherein a piston rod which is led in a sealed manner out of the associated front end of the housing is connected on one side of the piston, the movement of the furniture part to be damped being transmitted to the outer end of the piston rod remote from the piston, wherein an elongate adjustment shaft with a diameter corresponding substantially to the diameter of the piston rod is connected on the side of the piston opposite the working chamber on the piston rod side, and the free end of the adjustment shaft is likewise led in a sealed manner out of the end face of the housing lying opposite the closed end face on the piston rod side, wherein the adjustment shaft is disposed rotatably in the piston and has a throttle disc projecting radially from the circumferential surface thereof which in the region of one end of a piston passage bore which connects the two working chambers and forms the overflow connection abuts an end face of the piston, and the throttle disc is provided with a plurality of recesses with different passage cross-sections which are offset from one another in the circumferential direction and can be aligned selectively by rotation of the adjustment shaft with the passage bore which is provided in the piston and connects the working chambers.
(2) Description of Related Art
In furniture construction such damping or also decelerating devices serve for example to avoid or at least largely reduce the stresses and noise produced during rapid vigorous closing of doors or closing of drawers of cabinets during the jerky deceleration of the movable furniture part mounted on the carcass. Damping devices operating with viscous fluids, such as for example silicone oil, as damping medium (e.g. DE 103 00 732 A1) have the advantage over devices operating with gaseous damping medium that these fluid damping media are practically incompressible, so that they have no resilient properties, which seeks to move the movable furniture part back somewhat out of the actual closed position after the closed position is reached. When such dampers are used the problem arises that the damping forces to be generated for damping of the movable furniture part are also dependent upon the mass of the respective furniture part and the closing speed thereof, so that for different damping tasks different dampers are necessary which are appropriately adapted to the required damping characteristics.
In order to construct these known damping devices so that they are adjustable to different damping characteristics without conversion or replacement of individual parts, damping devices have been proposed (PCT/EP2007/008461, FIGS. 14 to 21) which are constructed in the manner described in the introduction and in which the damping characteristics are variable in a predetermined number of stages, e.g. in four stages, in that by rotation of the adjustment shaft and thus of the throttle disc a respective one of a plurality of recesses with different passage cross-sections in the throttle disc can be aligned with the passage bore in the piston which connects the working chambers. In this damping device—which was not prior-published—the throttle disc in the respective selected damping stage is against inadvertent rotation by a positive locking engagement. In this case in order to change over to another damping stage it is necessary first of all to interrupt this locking against rotation, which is possible by longitudinal displacement of the adjustment shaft against the initial tension of a tension spring. In this longitudinally displaced state the adjustment shaft can then be rotated into the desired damping stage. It can be seen that this design does indeed achieve a high degree of security against inadvertent alterations to a set damping characteristic but that the adjustment operation itself is complex and a correspondingly increased outlay on construction is necessary because of the requirement for exertion of a pretension and the displaceable mounting of the adjustment shaft.